Although vernal conjunctivitis (VC) appears to be an atopic disease, no direct evidence exists for an IgE-mediated pathogenesis. Nineteen patients with VC (16 males, 3 females, average age 14 4/12) were studied for the presence of specific IgE antibodies to the inhalant pollen allergens in tear secretions by the RAST (Pharmacia) technique. Results were expressed as % binding of the total 125I anti-IgE added. A positive RAST score (Class 1) using the reference standards gave greater than 2.91 plus or minus 0.19 (SEM) % binding. Control groups included normal non-atopic individuals (6) patients with allergic rhinitis (3) and allergic conjunctivitis (9). Specific IgE antibodies were detected in the tear secretions of 5 VC patients. In 3 of these patients the RAST values of the tears ranged from 3.3 to 7.8% binding, whereas the corresponding values in the serum ranged from 1.6 to 2.4% and the skin tests were negative. The other 2 patients had both positive skin tests and serum RAST. The RAST values in the tear secretions of these patients ranged from 9.8 to 43.5% binding. Using transferrin as a marker for the leakage of plasma proteins in to tear secretions, greater than 90% of the specific IgE antibodies were locally produced. The mean tear RAST values were 1.1 plus or minus 0.11% for the non-atopic individuals, 2.3 plus or minus 0.43% for the patients with allergic rhinitis and 1.5 plus or minus 0.17% for the patients with allergic conjunctivitis. These studies suggest that IgE may play a role in the pathogenesis of VC and may help identify the specific offending allergens.